Multistage linear motor with means for locking the stages thereof against relative rotary movement



Sept. 23, 1969 a. w. GALLOWAY ET AL 3,468,398

MULTISTAGE LINEAR MOTOR WITH MEANS FOR LOCKING THE STAGES THEREOFAGAINST RELATIVE ROTARY MOVEMENT Filed Jan. 8, 1968 INVENTORS. 66 64 WAATTOEA/fVS g6 flip I @W United States Patent MULTISTAGE LINEAR MOTORWITH MEANS FOR LOCKING THE STAGES THEREOF AGAINST RELATIVE ROTARYMOVEMENT I George W. Galloway, Arcadia, and Albert E. Blanchard,

Temple City, Calif., assignors to G. W. Galloway Company, Baldwin Park,Calif., a corporation of California Filed Jan. 8, 1968, Ser. No. 696,432Int. Cl. E04g 1/22; FOlb 7/20 US. Cl. 182141 12 Claims ABSTRACT OF THEDISCLOSURE A multistage linear motor particularly suited for use tosupport a vertically adjustable mast for a workmens station and havingsimple lock means for locking the components of the mast againstrelative rotary movement when stages thereof are extended or retracted.In one typical application, the motor assembly is mounted rigidlyupright on a mobile frame for use by a Workman while supported at thetop of the mast in different extended positions thereof.

This invention relates to linear motors and more particularly to animproved multistage motor of the axially extendable type and featuringpositive means for locking stages of the motor against relative rotatarymovement in either the extended or retracted positions of its respectivestages.

Multiple stage linear motor assemblies of a wide variety of designs havebeen proposed heretofore, including those having provision forminimizing relative rotary movement of the telescoping components. Suchantirotation provisions are particularly desirable and essential whenthe motor is being used as a hoist or mast to support workmen atdifferent elevations. Typically, these antirotation safeguards make useof elongated keys fixed lengthwise of all inner stage members andslidable through close fitting passage means facing inwardly of thecooperating larger diameter tubular members. Such an interlock is fairlysatisfactory if manufactured to close tolerances for motors of one or avery limited number of stages. Even in these cases the engaging surfacesof the key and its guide passage are subject to wear permitting anincreasing amount of play and rotary movement as the wear increases. Inthe case of motors having multiple stages, play associated with workingtolerances and wear are cumulate with the result that the workmensstation at the free end of the mast or motor can twist through an arc ofvery substantial size. Furthermore, the permitted movement is double themagnitude of the actual play if movement starts with the partspositioned in one extreme rotary position. For this reason, the totalmovement can reach highly objectionable proportions under theseconditions. It will also be recognized that the permitted movementoperates to aggravate conditions because of the higher impact and wearforces imparted to the contacting surfaces as wear and play increasesand when the rotary movement occurs rapidly and/or under high loadconditions.

The foregoing factors have imposed definite limitations on the practicallengths for linear motors for use in applications where theaforementioned relative movement is objectionable or hazardous topersonnel or property.

It is therefore a primary object of the present invention to provide animproved linear motor of one or more stages featuring positive meanseffective at either the extended or retracted positions of thecomponents to hold the components positively against relative rotarymovement. Typically, such locking means comprises a key fixed to alength of the smaller diameter component and having appropriately shapedtongue means at its opposite ends adapted to nest within complementallyshaped notch means formed in a suitably positioned part of thecooperating stage components, as for example, the sides of the passagethrough which the key reciprocates. Desirably, the tongue and notch areof wedge shape with one side of the wedge making an acuate with thelongitudinal axis of the motor and serving to cam the locking componentssnugly and immovably together as the motor moves into either its fullyextended or its fully retracted position. Associated with the tonguethere preferably is a safety stop ring encircling the smaller diametertube and accurately positioned to abut the adjacent surface of thebearing ing providing with the notches and passage through which thelocking key moves. This arrangement supplements the action of the notchand tongue in holding the stages rigidly against relative movement.

It is therefore a primary object of the present invention to provide animproved linear motor featuring positive means for locking thecomponents against relative movement when adjusted to one or morepositions thereof.

Another object of the invention is the provision of a linear motorhaving elongated key means fixed to one of its parts and havingclose-fitting sliding movement through a passage in a cooperatecomponent for minimizing relative rotary movement in intermediatepositions of the motor and featuring internesting tongue and notch meansat both extremes of motor movement for holding the parts positivelyagainst any substantial relative rotary movement.

Another object of the invention is the provision of a multi-stage mastfor workmen wherein each stage of the mast is provided with positiveinterlocking means for locking adjacent stages of the mast againstrelative rotary movement in the fully extended or fully retractedposition of any stage thereof.

These and other more specific objects will appear upon reading thefollowing specification and claims and upon considering in connectiontherewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of theinvention is illustrated.

FIGURE 1 is an elevation view of one preferred embodiment of theinvention constructed as embodied in a rnulti-stage hoist equipped witha Workmens station at its upper end.

FIGURE 2 is a fragmentary sectional view on enlarged scale showingdetails of the construction; and

FIGURE 3 is a cross-sectional view taken along line 33 on FIGURE 2.

Referring more particularly initially to FIGURE 1, there is shown ahydraulically operated linear motor designated generally it) having itslarger lower end rigidly fixed in an upright position to a main frame 11supported on wheels 12, 12. Outrigger struts 13 are equipped with rotaryscrews 14 having pads 15 at their lower ends engageable with the groundand cooperating to provide a Wide based firm support for main frame 11Whenever the equipment is in use. At other times the struts may beretracted and folded in known manner against the main frame, as whileequipment is stored or in transit to another place of use.

As herein illustrated, motor 14} is usable to support a workmens stationor cage 18 secured to its upper free end. Motor 18 comprises anysuitable number of stages, as 20, 21, 22, 23, sized to telescope axiallyof one another in well known manner. The upper end of each stage isprovided with a combined retainer and bearing ring 25 held detachablyassembled to the tubular section by snug fitting set screws 26, thisring being secured in place after the tubes have been assembled. Eachring has a passage 28 having a close sliding fit with the oppositeparallel sides of a key 29 extending for substantially the full lengthof the exterior of all except the largest stage 20. Key 29 is secured tothe sections in any suitable way, the mode here shown utilizing a seriesof holes 30 filled with brazing or welding material 31.

The opposite ends of each of keys 29 are provided along theirdiametrically opposed corners with a suitably shaped tongue 33 which isaccurately shaped complementally to a notch 35 formed in the oppositeends of each of the passages 28 through bearing rings 25. As hereinshown by way of example, tongues 33 are wedge shaped with one side wallforming an acute angle with respect to the longitudinal axis of keys 29.The corresponding side wall of each of notches 35 is of identical shapeas tongues 33 with the result that the tongues preferably have a snugfit throughout their length with the particular one of the notches withwhich it is paired. Owing to the acute angle of the tongues and notches,it will be apparent that the movement of any stage to its fully extendedor its fully retracted position results in the firm seating of one ofthe tongues in one of the notches. As pressure is applied to theassembly to extend the motor, the tongue at the lower end of stage 22enters the similarly shaped notch at the upper end of a surrounding tubeand acts to forcibly cam key 29 to the right as viewed in FIGURE 2. Inthis position one edge of key 28 is held pressed firmly against theadjacent side wall of passage 28, and the tongue 33 on the other edge ofthe key is held firmly and immovably pressed against the side wall ofnotch 35. Accordingly, stages 21 and 22 are forcibly held against rotarymovement in either direction. Hydraulic pressure applied to the interiormotor from its lower end acts on the piston heads 38 at the lower end ofeach stage to maintain the components locked in this non-rotaryposition. In this connection it is pointed out that each piston isprovided with a resilient sealing gasket 39 held in assembled position,as by cap screws 40. Each piston also includes a passage 41 to transmitfluid lengthwise of all stages.

Preferably, the lower end portion of each tubular section is alsoprovided with an accurately constructed and positioned safety stop ring42 secured to the tubing as by welding 43. The entire upper end edge 44of this ring is positioned to abut the adjacent end of bearing ring 25throughout its girth precisely as wedge tongue 33 seats fully withinnotch 35. In this way the powerful pressures acting to hold the motorextended are distributed throughout the girth of bearing ring 25 therebyavoiding having the full load carried by tongue 33. Additionally, thisarrangement is highly eifective in stabilizing the mast against lostmotion longitudinally thereof and aids very materially in rendering ithighly rigid and stable.

When one or more stages of the motor are retracted the upper one or onesof wedges 33 seat in the upwardly facing ones of notches 35 and theweight of overlying portions of the mast are highly effective in holdingthe wedge shaped tongues firmly and positively seated. It will also beevident that the described locking tongues and notches are not subjectto wear in use as are the relatively sliding side walls of passages 28and the adjacent lateral edges of keys 29. In consequence, thedescrcibed anti-rotation locking device remains highly eflicient andefiective throughout the life of the motor and virtually eliminates allpossibility of rotary movement between motor stages when the lockingcomponents are engaged.

While the particular multistage linear motor with means for locking thestages thereof against relative rotary movement herein shown anddisclosed in detail is fully capable of attaining the objects andpI'OVldlIlg the advantages hereinbefore stated, it is to be understoodthat it is merely illustrative of the presently preferred embodiments ofthe invention and that no limitations are intended to the details of theconstruction or design herein shown other than as defined in theappended claims.

We claim:

I. In a linear motor of the type having a plurality of tubular sectionshaving a close telescopic fit axially of one another together with meansfor moving said sections between first and second axially separatedpositions thereof; that improvement for locking said tubular sectionsagainst relative rotary movement when in one of said positions whichcomprises: complementally shaped notch means and tongue means eachrigidly fixed to a respective one of said tubular sections in positionto move into and out of snug interlocking engagement as said tubularsections approach and recede from said one position, said notch meansand said tongue means cooperating when fully engaged to lock saidtubular sections positively against relative rotary movement and beingreadily disengageable from locked position by limited axial movement ofsaid tubular member toward the second of said positions.

2. A linear motor as defined in claim 1 characterized in that saidtubular sections are provided with complementally shaped notch means andtongue means at each of said first and second positions of said tubularsections.

3. A linear motor as defined in claim 1 characterized in the provisionof close fitting key and groove means extending lengthwise of saidtubular members between said first and second positions thereof andcooperating to limit relative rotary movement of said tubular sectionsWhile positioned in partially extended positions between said first andsecond positions.

4. A linear motor as defined in claim 3 characterized in that saidtongue means is located near one end of said key means and in that saidnotch means is located near one end of the groove means slidably seatingsaid key means.

5. A linear motor as defined in claim 4 characterized in that said keymeans is provided with tongue means near each end thereof and that thegroove means slidably seating said key means includes separate notchmeans positioned to seat a respective one of said tongue means depending upon which of said first and second positions is occupied bysaid tubular sections.

6. A linear motor as defined in claim 5 characterized in that saidgroove means extends transversely of annular bearing ring meanspositioned between the telescoped ends of said tubular sections.

7. A multi-stage linear motor assembly adapted to be operated under loadbetween a fully contracted position and dilferent extended positions ina plurality of which positions all stages are positively locked againstrelative rotary movement about the axis of said motor assembly, saidmotor assembly comprising a plurality of tubular sections assembled inaxially-adjustable fluid-tight telescopic relation and including ringmeans between the overlapping ends of adjacent sections, elongated keymeans fixed to and extending lengthwise of all except the largest ofsaid tubular sections and having a close sliding fit with a passageextending crosswise of said ring means, and the opposite ends of saidpassage having oppositely facing notches each adapted to seat snugly anassociated complementally shaped tongue means fixed to the opposite endsof each of said key means when an adjacent pair of said sections is ineither the fully extended or the fully retracted positions thereof.

8. A linear motor assembly as defined in claim 7 characterized in thatsaid interlocking notch and tongue means are wedge shaped with one sideof the wedge extending axially of said key means at an acute angle tothe adjacent lateral edge of said key means whereby the contactinginclined sides of a notch and a wedge cooperate in forcing the key meansagainst that side of said passage which is spaced remotely from saidnotch means.

9. A linear motor assembly as defined in claim 8 characterized in theprovisions of a plurality of fastener means mounted in the exposed outerends of said tubular sections for holding said ring means detachablyassembled to said sections.

10. A linear motor assembly as defined in claim 9 characterized in theprovision of safety stop means spaced backwardly from the innermost endof said tubular sections and fixed thereto and cooperating with saidring means to safeguard against over extension of said tubular sections.

11. A linear motor assembly as defined in claim 10 characterized in thatsaid safety stop means is positioned 10 assembly is rigidly supported inan upright position on a mobile rigid frame, and in that the uppersmaller end of said motor assembly is provided with a workmenssupporting means rigidly secured thereto.

References Cited UNITED STATES PATENTS 3,091,305 5/1963 Pickard 1821411,033,430 7/1912 Matheson 285302 FOREIGN PATENTS 750,541 5/1933 France.

REINALDO P. MACHADO, Primary Examiner US. Cl. X.R. 92-52

